1. Field of the Invention
The present invention is related to an apparatus for manufacturing an organic film which is to be applied to a substrate. In addition, the present invention is a method for manufacturing an organic functional device such as an organic electroluminescence device (hereinafter, called an organic EL), an organic solar cell and an organic transistor, the method including a drying process.
2. Description of the Related Art
In late years, development of an organic functional device such as an organic EL device, an organic solar cell and an organic transistor using an organic functional material has been active in order to obtain a flexible or thin and light electronic member. It is necessary that a pattern of an organic functional layer having a thickness of, generally, several tens—several thousands nm is formed on a substrate in the case of manufacturing these organic functional devices.
Low molecular materials and polymeric materials are examples of organic functional materials. Generally, as for low molecular materials, thin film can be formed by a resistance heating vapor deposition method. A mask with minute patterns is used at this time, and patterns are formed. In a manufacturing method with the use of this method, upsizing of a substrate can diminish the accuracy of the patterning. In addition, in a vapor deposition method, a source of a vapor is usually a small aperture such as a pinhole of a boat or a crucible. Therefore, it is difficult to form a uniform layer on an upsized substrate. In addition, it is often that a vapor deposition method is performed under high vacuum. Therefore, a large-sized vacuum apparatus is necessary.
On the other hand, a method of forming a thin film by a wet process with a coating liquid (an ink) obtained by dispersing or dissolving the organic functional material into a solvent has been attempted. As the wet coating method for the thin film formation, spin coating, bar coating, projection coating, dip coating, and the like are known. It is considered that the thin film of high definition pattern is most effectively formed by a printing process that is capable of achieving excellent color coding and patterning. (For example, see patent documents 1, 2 and 3, and non-patent document 1.)
A method for manufacturing an organic functional device by a printing method is very effective. Especially, in the case where a high molecular material is used, a pattern of a flat and uniform organic functional layer can be easily formed on a substrate. However, since an organic functional layer printed on a substrate includes a solvent, a drying step for removing the solvent is necessary. Examples of proposed methods for the drying step include a vacuum oven method (for example, see patent document 4.), a heat drying method (for example, see patent document 5.) and a pressurized heat drying method (for example, see patent document 6.).
However, in the case where an organic functional device is manufactured by forming an organic functional layer on a substrate by a printing method such as a relief printing method (a flexo printing method), an intaglio offset printing method, a relief printing type reverse offset printing method, an ink jet printing method and an intaglio printing method, a solvent having a very high boiling point at atmospheric pressure (ex. more than 150 degrees Celsius) is often used in order to prevent a drying of a coating liquid during a printing process. It is impossible that a solvent can not be sufficiently removed from an organic functional layer by a heat drying under an atmospheric pressure, a reduced pressure and an increased pressure. Further, there is a problem that characteristics of an organic functional device are reduced or degraded due to the high boiling point solvent remaining in an organic functional layer, compared with a case where a high boiling point solvent is not used. It is thought that such degradation is caused by chemical reaction of a remaining high boiling point solvent with an organic functional material or an inorganic electrode. In addition, the following phenomenon may occur: after an organic functional layer is formed, an inorganic film etc. is formed by a vacuum method such as a vapor deposition method or a sputtering method; at this time, a chamber is polluted with a little vaporized high boiling point solvent remaining in an organic functional layer; thereafter, an inorganic film formed in the same chamber may badly influenced.
In addition, in the case where an organic functional layer is heated to a high temperature in order to remove a solvent (a first organic solvent: hereinafter, it may be called as a remaining solvent.) remaining in an organic functional layer by a sufficient drying, materials of an organic functional device may be degraded. In addition, further, in the case where a film made of a plastic is used for a substrate in order to make a light and flexible device, there is a problem in which change of form or degradation of a substrate occurs by a high heat. Besides, in the case where there is oxygen or water with an organic functional layer in heating, there is a problem in which oxygen or water chemically reacts with an organic functional layer, thereby characteristics of device are degraded. Especially, oxygen easily reacts with a double bond part of a π electron system molecule which is frequently used as an organic functional layer. Therefore, in the case where an organic functional layer is dried at a high temperature, drying is often performed in a non-active atmosphere such as nitrogen or argon.
Therefore, the present invention was made by considering the above-mentioned facts. The present invention provides a method and an apparatus for manufacturing an organic film by which a high performance organic functional device can be manufactured. In the method and the apparatus, degradation of characteristics of an organic functional device due to a removal of a remaining solvent does not occur in the case where an organic functional layer is manufactured by a printing method. Further, the present invention provides a method for manufacturing an organic EL device, an organic solar cell and an organic transistor, in which a method for manufacturing an organic film provided by the present invention is used.    [Patent document 1] JP-A-2003-17261    [Patent document 2] JP-T-2003-527955    [Patent document 3] JP-T-2005-531134    [Patent document 4] JP-A-H09-97679    [Patent document 5] JP-A-2002-313567    [Patent document 6] JP-A-2005-26000    [Non-patent document 1] 5th time of 142nd committee [of organic materials] C sectional meeting (organic optoelectronics) study group data for information science Organic thin film solar cell by a printing process (20-27 pages)